This invention relates to ceramic matrix components for gas turbines and, specifically, to testing of ceramic matrix turbine bucket shrouds.
The present invention relates to a support and damping system for ceramic shrouds surrounding rotating components in a hot gas path of a turbine and particularly relates to a spring mass damping system for interfacing with a ceramic shroud and tuning the shroud to minimize vibratory response from pressure pulses in the hot gas path as each turbine blade passes the individual shroud.
Ceramic matrix composites offer advantages as a material of choice for shrouds in a turbine for interfacing with the hot gas path. The ceramic composites offer high material temperature capability. It will be appreciated that the shrouds are subject to vibration due to the pressure pulses of the hot gases as each blade or bucket passes the shroud. Moreover, because of this proximity to high-speed rotation of the buckets, the vibration may be at or near resonant frequencies and thus require damping to maintain life expectancy during long-term commercial operation of the turbine. Ceramic composites, however, are difficult to attach and have failure mechanisms such as wear, oxidation due to ionic transfer with metal, stress concentration and damage to the ceramic composite when configuring the composite for attachment to the metallic components. Accordingly, there is a need for responding to dynamics-related issues relating to the attachment of ceramic composite shrouds to metallic components of the turbine to minimize adverse modal response.
Ceramic matrix composites can withstand high material temperatures and are suitable for use in the hot gas path of gas turbines. Recently, melt-infiltrated (MI) silicon-carbon/silicon-carbon (SiC/SiC) ceramic matrix composites have been formed into high temperature, static components for gas turbines. Because of their heat capability, ceramic matrix composite turbine components, e.g., MI-SiC/SiC components, generally do not require or reduce cooling flows, as compared to metallic components.